Hereditary Benign Intraepithelial Dyskeratosis (HBRID) is an autosomal dominant cell proliferation disorder characterized by opaque epithelial plaques on the optical conjuctiva and oral mucosa. The large plaques are elevated, granular, and white to gray in color. They appear at birth or in early childhood, can involve the cornea, and can obstruct the vision. They are also accompanied by hyperemic blood vessels, giving the eye a very red or bloodshot appearance. HBID is found primarily among members of the Haliwa-Saponi Indian Tribe and their relatives. The characteristic "red eye" appearance leads to many difficulties in social interactions and employment, because strangers often presume affected individuals are under the influence of drugs. We have linked the gene for this disorder to chromosome 4q35 with a peak multipoint lod score of 11.58. We have discovered a DNA duplication in this region that is the most likely cause of the disease. In the present application, we propose to extend our investigations into the etiology of this disorder. The role that the DNA duplication plays in HBID will be evaluated by a detailed molecular analysis of the duplicated region and candidate genes. We will also follow the clinical course in affected individuals, using surgical specimens to establish cultured cell lines from conjunctival lesions.